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Virtual source approach for maximizing resolution in high-penetration gamma-ray imaging

Matter and Radiation at Extremes 2024年第3期9卷 19-30页

作者： Yuchi Wu Shaoyi Wang bin Zhu Yonghong Yan Minghai Yu Gang Li Xiaohui Zhang Yue Yang Fang Tan Feng Lu bi bi Xiaoqin Mao Zhonghai Wang Zongqing Zhao Jingqin Su Weimin Zhou Yuqiu Gu National Key Laboratory of Plasma Physics Laser Fusion Research CenterCAEPMianyangSichuan 621900China College of Physics Sichuan UniversityChengdu 610065China

High-energy gamma-ray radiography has exceptional penetration ability and has become an indispensable nondestructive testing(NDT)tool in various *** high-energy photons,point projection radiography is almost the only feasible imaging method,and its spatial resolution is primarily constrained by the size of the gamma-ray *** conventional industrial applications,gamma-ray sources are commonly based on electron beams driven by accelerators,utilizing the process of bremsstrahlung *** size of the gamma-ray source is dependent on the dimensional characteristics of the electron *** research has been conducted on various advanced accelerator technologies that have the potential to greatly improve spatial resolution in *** our investigation of laser-driven gamma-ray sources,a spatial resolution of about 90μm is achieved when the areal density of the penetrated object is 120 g/cm^(2).A virtual source approach is proposed to optimize the size of the gamma-ray source used for imaging,with the aim of maximizing spatial *** this virtual source approach,the gamma ray can be considered as being emitted from a virtual source within the convertor,where the equivalent gamma-ray source size in imaging is much smaller than the actual emission *** the basis of Monte Carlo simulations,we derive a set of evaluation formulas for virtual source scale and gamma-ray emission *** optimal conditions,the virtual source size can be as small as 15μm,which can significantly improve the spatial resolution of high-penetration imaging to less than 50μm.

关键词： resolution approach utilizing

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Recent progress in printing flexible electronics: A review

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Science China(Technological Sciences) 2024年第8期67卷 2363-2386页

作者： bi Sheng GAO BuHan HAN Xu HE ZhengRan METTS Jacob JIANG ChengMing ASARE-YEBOAH Kyeiwaa Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education School of Mechanical EngineeringDalian University of TechnologyDalian 116024China Center for Materials for Information Technology The University of AlabamaTuscaloosaAL 35487USA Department of Electrical and Computer Engineering Penn State BehrendEriePA 16563USA

Miniaturization and flexibility are becoming the trend in the development of electronic products. These key features are driving new methods in the manufacturing of such products. Printed electronics technology is a novel additive manufacturing technique that uses active inks to print onto a diverse set of substrates, realizing large-area, low-cost, flexible and green manufacturing of electronic products. These advantageous properties make it extremely compatible with flexible electronics fabrication and extend as far as offering revolutionary methods in the production of flexible electronic devices. In this paper, the details of a printing process system are introduced, including the materials that can be employed as inks, common substrates, and the most recently reported printing strategies. An assessment of future setbacks and developments of printed flexible electronics is also presented.

关键词： flexible electronics printing process conductive ink flexible substrate

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Efficient and fair PPO-based integrated scheduling method for multiple tasks of SATech-01 satellite

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Chinese Journal of Aeronautics 2024年第2期37卷 417-430页

作者： Qi SHI Lu LI Ziruo FANG Xingzi bi Huaqiu LIU Xiaofeng ZHANG Wen CHEN Jinpei YU Shanghai Satellite Network Research Institute CO. LTDShanghai 201210China Innovation Academy for Microsatellites of Chinese Academy of Sciences Shanghai 201306China University of Chinese Academy of Sciences Beijing 100039China

SATech-01 is an experimental satellite for space science exploration and on-orbit demonstration of advanced *** satellite is equipped with 16 experimental payloads and supports multiple working modes to meet the observation requirements of various *** to the limitation of platform power supply and data storage systems,proposing reasonable mission planning schemes to improve scientific revenue of the payloads becomes a critical *** this article,we formulate the integrated task scheduling of SATech-01 as a multi-objective optimization problem and propose a novel Fair Integrated Scheduling with Proximal Policy Optimization(FIS-PPO)algorithm to solve *** use multiple decision heads to generate decisions for each task and design the action mask to ensure the schedule meeting the platform *** results show that FIS-PPO could push the capability of the platform to the limit and improve the overall observation efficiency by 31.5%compared to rule-based plans currently ***,fairness is considered in the reward design and our method achieves much better performance in terms of equal task *** of its low computational complexity,our task scheduling algorithm has the potential to be directly deployed on board for real-time task scheduling in future space projects.

关键词： Satellite observatories SATech-01 Multi-modes platform Scheduling algorithms Reinforcement learning Proximal Policy Optimization(PPO)

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High‑Entropy Layered Oxide Cathode Enabling High‑Rate for Solid‑State Sodium‑Ion Batteries

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Nano-Micro Letters 2024年第1期16卷 160-171页

作者： Tianxun Cai Mingzhi Cai Jinxiao Mu Siwei Zhao Hui bi Wei Zhao Wujie Dong Fuqiang Huang State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050People’s Republic of China State Key Laboratory of Rare Earth Materials Chemistry and Applications College of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871People’s Republic of China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049People’s Republic of China Zhongke Institute of Strategic Emerging Materials Yixing 214213JiangsuPeople’s Republic of China

Na-ion O3-type layered oxides are prospective cathodes for Na-ion batteries due to high energy density and ***,such cathodes usually suffer from phase transitions,sluggish kinetics and air instability,making it difficult to achieve high performance solid-state sodium-ion ***,the high-entropy design and Li doping strategy alleviate lattice stress and enhance ionic conductivity,achieving high-rate performance,air stability and electrochemically thermal stability for Na_(0.95)Li_(0.06)Ni_(0.25)Cu_(0.05)Fe_(0.15)Mn_(0.49)O_(2).This cathode delivers a high reversible capacity(141 mAh g^(−1)at 0.2C),excellent rate capability(111 mAh g^(−1)at 8C,85 mAh g^(−1)even at 20C),and long-term stability(over 85%capacity retention after 1000 cycles),which is attributed to a rapid and reversible O3–P3 phase transition in regions of low voltage and suppresses phase ***,the compound remains unchanged over seven days and keeps thermal stability until 279℃.Remarkably,the polymer solid-state sodium battery assembled by this cathode provides a capacity of 92 mAh g^(−1)at 5C and keeps retention of 96%after 400 *** strategy inspires more rational designs and could be applied to a series of O3 cathodes to improve the performance of solid-state Na-ion batteries.

关键词： High-entropy High-rate performance Li-TM interaction Air stability O3 layered oxide cathode

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Microplastic and Heavy Metals Distributions in Urban Rivers Sediments,China

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Journal of Ocean University of China 2024年第4期23卷 1015-1025页

作者： SONG Dandan SHANG Yujun WANG Xiuli ZHUANG Yuwei GUO Hui bi Shuping HU Jianjun High and New Technology Research Center of Henan Academy of Sciences Zhengzhou 450002China Henan Provincial Cartographic Institute Zhengzhou 450008China

This study investigated the distribution of microplastics and heavy metals,along with the interaction between the two in the sediments of urban rivers in *** showed that the abundance of microplastics ranged from 2412±187.5 to 7638±1312items kg^(-1)dry sediment across different survey stations,with an average abundance at(4388±713)items kg^(-1)dry *** further categorization,it was found that transparent fragments were the primary color and type of microplastics *** potential ecological risk index(RI)of heavy metals in sediments suggested a low level of ecological risk within a majority of the urban rivers *** was identified as the main potential ecological risk factor in the sediments of the studied *** was a relatively good significant linear relationship between the RI of heavy metals and the abundance of microplastics,bolstering the linkage between these two environmental ***,the concentrations of heavy metals in microplastics were not dependent on their corresponding contents in *** fact,the concentration of Cu,Cd,and As in microplastics were higher than those in the *** finding confirmed that microplastics could serve as carriers of heavy metals and introduce potential risks to aquatic wildlife and human through the food chain.

关键词： microplastic heavy metals risk assessment river sediments

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Investigation on the vortical structures by the Liutex method in turbulent channels at Re_(τ)=180 with scalloped and triangular riblet control

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Journal of Hydrodynamics 2024年第1期36卷 35-52页

作者： Zhang-dan Yu Shang Jiang Hai-dong Yu bi-yu Pang Xin Dong Yi-qian Wang School of Mathematical Sciences Soochow UniversitySuzhou215006China Beijing Institute of Astronautical System Engineering Beijing100076China

Riblets are a series of small protrusions formed along the flow direction,which have been extensively studied as a passive turbulent drag reduction *** and numerical simulations have shown that well-designed riblets can significantly reduce drag in turbulent flows,making them highly promising and valuable for various *** this study,we focus on a scalloped riblet,which is designed by smoothly connecting two third-order polynomials,and thus the sharpness of the tip and the curvature of the valley can be well *** conduct direct numerical simulations of turbulent channel with smooth plate,scalloped riblet-mounted and triangular riblet-mounted *** in wall units of W^(+)=20 and height-width ratio ofγ=0.5 are selected for both riblet *** with the smooth plate case,the scalloped riblet case achieves an 8.68%drag reduction,while the triangular riblet case achieves a 4.79%drag *** obtained drag reduction rate of the triangular riblet is consistent with previous experiments and simulations,and the results indicate that the scalloped riblet is more effective in reducing drag and deserves further *** compare turbulent statistics of the scalloped riblet case with those of the triangular riblet *** mean velocity profiles of riblets are similar,but both the Reynolds shear stress and second-order statistics of velocity fluctuations and Liutex are significantly reduced in the scalloped riblets controlled turbulent channel,indicating that the scalloped riblet can more effectively suppress the spanwise and wall-normal turbulent intensity near the *** also compare the pre-multiplied spectra of streamwise velocity and streamwise Liutex component for the three cases to investigate the energy distribution and characteristics of Liutex *** Liutex vortex identification method is also utilized to analyze the instantaneous flow field,which provides insights into the flow field and could be bene

关键词： Liutex vector riblet drag reduction tip sharpness turbulent channel scalloped

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Efficient Dynamic Locomotion of Quadruped Robot via Adaptive Diagonal Gait

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Journal of bionic Engineering 2024年第1期21卷 126-136页

作者： Jian bi Teng Chen Xuewen Rong Guoteng Zhang Guanglin Lu Jingxuan Cao Han Jiang Yibin Li The Center for Robotics School of Control Science and EngineeringShandong UniversityJi Nan 250000China

Quadruped animals in the nature realize high energy efficiency locomotion by automatically changing their gait at different *** by this character,an efficient adaptive diagonal gait locomotion controller is designed for quadruped robot.A unique gait planning method is proposed in this *** the speed of robot varies,the gait cycle time and the proportion of stance and swing phase of each leg are adjusted to form a variety of *** optimal joint torque is calculated by the controller combined with Virtual Model Control(VMC)and Whole-Body Control(WBC)to realize the desired *** gait and step frequency of the robot can automatically adapt to the change of *** experiments are done with a quadruped robot made by our laboratory to verify that the gait can change automatically from slow-trotting to flying-trot during the period when speed is from 0 to 4 m/*** ratio of swing phase is from less than 0.5 to more than 0.5 to realize the running motion with four feet off the *** have shown that the controller can indeed consume less energy when robot runs at a wide range of speeds comparing to the basic controller.

关键词： Quadruped robot Gait transition Adaptive gait Energy efficiency

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A critical review on direct catalytic hydrogasification of coal into CH_(4):catalysis process configurations,evaluations,and prospects

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International Journal of Coal Science & Technology 2024年第3期11卷 51-85页

作者： Shuai Yan Jun Feng Shenfu Yuan Zihong Xia Fengshuang Han Xuan Qu Jicheng bi School of Materials and Chemical Engineering Ningbo University of TechnologyNingbo315211ZhejiangChina Zhejiang Institute of Tianjin University Ningbo315201ZhejiangChina State Key Laboratory of Coal Conversion Institute of Coal ChemistryChinese Academy of SciencesTaiyuan030001China School of Chemical Science and Engineering Key Laboratory of Medicinal Chemistry for Natural ResourceMinistry of EducationNational Center for Experimental Chemistry and Chemical Engineering Education DemonstrationYunnan Provincial Key Laboratory of Carbon Neutral and Green Low-Carbon TechnologyYunnan UniversityKunming650091China Department of Energy and Chemical Engineering East China University of Science and TechnologyShanghai200237China

Coal catalytic hydrogasification(CCHG)is a straightforward approach for producing CH_(4),which shows advantages over the mature coal-to-CH_(4) technologies from the perspectives of CH_(4) yield,thermal efficiency,and CO_(2) *** core of CCHG is to make carbon in coal convert into CH_(4) efficiently with a *** the past decades,intensive research has been devoted to catalytic hydrogasification of model carbon(pitch coke,activated carbon,coal char).However,the chemical process of CCHG is still not well understood because the coal structure is more complicated,and CCHG is a combination of coal catalytic hydropyrolysis and coal char catalytic *** review seeks to shed light on the catalytic process of raw coal during *** configuration of suitable catalysts,operating conditions,and feedstocks for tailoring CH_(4) formation were identified,and the underlying mechanisms were *** on these results,the CCHG process was evaluated,emphasizing pollutant emissions,energy efficiency,and reactor ***,the opportunities and strategic approaches for CCHG under the restraint of carbon neutrality were highlighted by considering the penetration of“green”H2,biomass,and CO_(2) into *** investigations from our laboratories demonstrated that the integrated CCHG and biomass/CO_(2) hydrogenation process could perform as an emerging pathway for boosting CH_(4) production by consuming fewer fossil fuels,fulfilling the context of green *** work not only provides systematic knowledge of CCHG but also helps to guide the efficient hydrogenation of other carbonaceous resources such as biomass,CO_(2),and coal-derived wastes.

关键词： Coal gasification Catalytic hydrogasification Methane Pressurized fluidized bed

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Explainable AI-Based DDoS Attacks Classification Using Deep Transfer Learning

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Computers, Materials and Continua 2024年第3期80卷 3785-3802页

作者： Alzu’bi A. Albashayreh A. Abuarqoub A. Alfawair M.A.M. Department of Computer Science Jordan University of Science and Technology Irbid 22110 Jordan Department of Computer Science The University of Jordan Amman 11942 Jordan Cardiff School of Technologies Cardiff Metropolitan University Cardiff CF5 2YB United Kingdom Prince Abdullah bin Ghazi Faculty of Information and Communication Technology Al-Balqa Applied University Salt 19117 Jordan

In the era of the Internet of Things (IoT), the proliferation of connected devices has raised security concerns, increasing the risk of intrusions into diverse systems. Despite the convenience and efficiency offered by IoT technology, the growing number of IoT devices escalates the likelihood of attacks, emphasizing the need for robust security tools to automatically detect and explain threats. This paper introduces a deep learning methodology for detecting and classifying distributed denial of service (DDoS) attacks, addressing a significant security concern within IoT environments. An effective procedure of deep transfer learning is applied to utilize deep learning backbones, which is then evaluated on two benchmarking datasets of DDoS attacks in terms of accuracy and time complexity. By leveraging several deep architectures, the study conducts thorough binary and multiclass experiments, each varying in the complexity of classifying attack types and demonstrating real-world scenarios. Additionally, this study employs an explainable artificial intelligence (XAI) AI technique to elucidate the contribution of extracted features in the process of attack detection. The experimental results demonstrate the effectiveness of the proposed method, achieving a recall of 99.39% by the XAI bidirectional long short-term memory (XAI-biLSTM) model. Copyright © 2024 The Authors. Published by Tech Science Press.

关键词： cybersecurity DDoS attack classification deep learning explainable AI

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Multi-wavelength Brillouin erbium-doped fiber laser with 40 GHz frequency shift interval assisted by Sagnac loop filter

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Optoelectronics Letters 2024年第5期20卷 265-271页

作者： QI Hexin ZHOU Xuefang ZHANG Yinghui YANG Guowei bi Meihua HU Miao School of Communication Engineering Hangzhou Dianzi UniversityHangzhou 310018China

A switchable and tunable multi-wavelength Brillouin erbium-doped fiber laser(MWBEFL) is designed and experimentally demonstrated. A Sagnac loop filter is employed as the switcher to obtain the double Brillouin frequency shift(BFS) of 0.172 nm(~20 GHz) and the quadruple BFS of 0.35 nm(~40 GHz). The working principles of the proposed laser are theoretically analyzed. The experimental results show that up to 8 Stokes lines with a wavelength interval of 0.172 nm can be obtained. When the Sagnac loop filter is used, two different output spectra with wavelength interval of 0.35 nm are obtained by adjusting the polarization controller(PC) and the optical signal-to-noise ratio(OSNR) is greater than 33 dB. By adjusting the Brillouin pump(BP) wavelength to investigate the tunability of the fiber laser, the output of 2—5 laser channels can be realized corresponding to 20 nm wavelength range. This approach is simple and can be employed for the microwave generation of other frequency ranges subject to the filtering shift of the Sagnac loop.

关键词： fiber laser filter

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